In existing online marketing systems, virtual catalogs may be created, such that a shopper may purchase products from the virtual catalog while shopping online. Typically, data for the virtual catalog may be provided by multiple sources. In some cases, a single product may be described differently in different portions of the virtual catalog, depending upon respective sources of data used to produce the different portions of the virtual catalog. For example, one product may be appear in different portions of the virtual catalog with different prices, or one item may appear in different portions of the virtual catalog with descriptions having conflicting information.